There has been known a rotary compression-molding machine including a table of a turret having die bores, and an upper punch and a lower punch slidably retained above and below each of the die bores, and configured to horizontally rotate the die bores and the punches together to compression mold or tablet a powdery material filled in the die bores when the paired upper and lower punches pass between an upper roll and a lower roll (see, for example, JP 2015-164740 A).
The molding machine of this type is typically configured to spray to apply a lubricant to an inner circumferential surface of each of the die bores and tips before filling the die bores with the powdery material and compression molding. The lubricant prevents the powdery material from adhering to the die bores and the punches, and examples thereof include wax made of magnesium stearate or the like, and talc.
The lubricant can preliminarily be mixed with the powdery material to be filled in the die bores as a constituent material for molded products. Examples of an additive to be added to a principal agent (i.e., a main ingredient or an active ingredient) include such an internal lubricant as well as an excipient appropriately increasing volume and weight of the molded products, a binder binding particles of the powdery material, and a disintegrant absorbing moisture to enable easy disintegration of the molded products. Examples of the disintegrant include starch, crystalline cellulose, and a carbonate.
A molded product production site can have serious tableting failure like binding of the powdery material remaining on the inner circumference of the die bore to obtain a chipped molded product, sticking of the powdery material remaining at the punch tip to obtain a chipped-molded product, and capping to obtain a broken-molded product. The molded product can also have inadequate hardness.
High friction between the molded product compressed in the die bore and the inner circumference of the die bore leads to high pressure applied to the lower punch that is pushing the molded product out of the die bore. This may cause abrasion or damage of a cam rail engaged with a head of the lower punch to push the lower punch upward or the head of the lower punch.